Discrete Headphone Amp.

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I always use jfets or small signal mosfets in the input stage so that I can use the unity gain DC feedback scheme of my choice with reasonable values of coupling film caps.

Take a look at post #19 of this thread to see what I mean.

Feedback capacitor to minimize DC offset

For the schematic shown in this thread, mosfets give better sim results, though it is possible to use Darlintons in the bottom side "fake SIT" output.
 
I just pulled the trigger this morning and ordered 3 sets of boards at PCBway (15 boards, 56 bucks, almost half of that DHL shipping - such a deal). One of those boards will be the next take on my single-ended project described elsewhere in the section, The other two exploit alternate output stage drive schemes - one uses an Aleph-style modulated current source, while the other uses a depletion mode mosfet in a variant of the old White cathode follower circuit. Both will get their day in the sun one I get the boards in and populate them. Both decouple the output bias from the input tail current, unlike the original approach shown here.
 
Here's a foretaste of things to come...
 

Attachments

  • Aleph_HP_SCH.GIF
    Aleph_HP_SCH.GIF
    30.9 KB · Views: 215
  • Aleph_HP_DIS..GIF
    Aleph_HP_DIS..GIF
    14 KB · Views: 215
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.